Sonar technology finds many applications in the field of fishing by assisting in the location of optimum fishing sites based upon the depth of the water and the location of fish or other underwater obstacles. Sonar devices include a sonar transducer which transmits ultrasonic signals which travel outward from the transducer, such as in a downward direction, until striking the bottom of the body of water, a fish or other obstacles in the body of water. Upon striking the bottom of the body of water, a fish, or another obstacle, the ultrasonic signals are reflected, thereby creating echo signals which are received by the transducer. The sonar device can then convert the echo signals to electronic signals indicative of the contour of the bottom of the body of water as well as the relative location of other obstacles or fish within the water. The sonar device can also display a visual representation of these electronic signals, such as on a visual display.
Sonar devices are conventionally mounted on fishing boats and are powered by the boat's power source. These devices often include a sonar transducer which is often permanently mounted to the transom or hull of a boat. Accordingly, only fishing sites permitting boat navigation may be investigated with the sonar transducer, thereby limiting the applications in which these sonar devices can be employed. Such devices are also relatively expensive, particularly in instances where excessive licensing fees are imposed. Also, such devices are impractical in smaller bodies of water such as ponds and shallow rivers, when weather conditions render boat navigation hazardous, or when boating is prohibited. Indeed, such devices require access to a boat and a relatively large body of water to attain the full benefit of the sonar transducer's fish finding capabilities.
Sonar devices have been developed which are designed to locate fish in instances in which an angler is not positioned within a boat. Such devices, however, have often been structurally complicated, expensive to manufacture, are not versatile, and have not provided optimum arrangements for transmitting and receiving the ultrasonic and electrical signals. For example, U.S. Pat. No. 5,495,680 to Cassem is directed to a relatively complex fish finding device employing sonar fish finding capabilities which may be mounted to a bank. The Cassem device is generally akin to a fishing pole, albeit with no fishing line. The "pole" is mounted to the ground at one end and supports a sonar transducer assembly at its other end. Due to the weight of the sonar transducer assembly, however, the pole is bowed so that its tip extends beneath the surface of the water in order to properly position the sonar transducer. The Cassem device also includes an electrical cable which extends along the pole between the sonar transducer and a display device such that a visual representation of the bottom surface of the body of water and the relative location of objects within the water can be provided. The Cassem system does, however, require a separate fishing pole for fishing.
U.S. Pat. No. 5,463,597 to Harlev is directed to a fishing pole having a sonar transducer extending therefrom. The fishing line of the Harlev fishing pole is, in one embodiment, a cable which provides electrical communication between the sonar transducer and a visual display. The sonar transducer of the Harlev fishing pole is mounted within a spherical float in the form of a conventional bobber. Therefore, the electrical cable not only electrically connects the visual display and the sonar transducer, but also serves as the fishing line such that movement of the fishing hook imparts movement to the sonar transducer, thereby disturbing the sonar readings. Thus, if the fishing line of the Harlev device contacts an underwater obstacle or is moved by a fish, the sonar transducer is likewise moved and the received and/or transmitted sonar signals are disturbed. Further, the spherical float has a relatively small surface area which, inherently, does not provide a stable float for the transducer in rough waters since the spherical float will tend to bob about in the water, thereby further disturbing the sonar readings by altering the relative position of the sonar transducer to the surface of the water. Indeed, these prior devices, as exemplified by the above-described patents, fail to provide an effective, efficient and easy manner of using sonar technology for fish finding applications when fishing from a bank or other fixed surface.